Theft alarm operable by vibration

ABSTRACT

An alarm is attached to a device such as a bicycle and operates when the device is moved. The alarm is controlled by a key switch which is turned on when the device is left unattended and must be turned off to de-energize the alarm. Within a casing is a vibration switch consisting of a weight on a flexible wire contained within a tube. Vibration and/or displacement from rest position causes the weight to establish momentary electric contact with the tube. The electric circuit contains a latching element such as a silicon controlled rectifier, the gate of which is connected to the vibration switch. With the key switch on, moving the device causes the weight to contact the tube, latching the rectifier on, and causing the buzzer to sound until the key switch is turned off.

United States Patent 11 1 Hamann et al.

1 51March 20, 1973 THEFT ALARM OPERABLE BY VIBRATION Inventors:yictoriaHamann, 1032 El Camino' Real, 86111006940025, Jack Dawson, 2206Darmelita Drive, San Carlos 94070, both of Calif.

Filed: Feb. 8, 1971 Appl. No.: 113,409

US. 01. ......340/65, zoo/61.49, 340/261 1111. CL; ..B60r 25/10 Field 6:Search.340/65, 261; zoo/61.52, D10. 8,

. ZOO/61.49

References Cited UNITED STATES PATENTS 1/1971 Hall et a1. 340/261 8/1967S loan'et al.... 11/1955 Toepfer 5 12/1964 Primary Examiner-John W.Caldwell Assistant Examiner-Glen R. Swann, Ill

Attorney-Julian Caplan and Gregg, Hendricson 8L Caplan [5 7] ABSTRACT Analarm is attached to a device such as a bicycle and operates when thedevice is moved. The alarm is controlled by a key switch which is turnedon when the device is left unattended and must be turned off todeenergize the alarm. Within a casing is a vibration switch consistingof a weight on a flexible wire con- 1 Claim, 4 Drawing Figures THEFTALARM OPERABLE BY VIBRATION SUMMARY OF THE INVENTION This inventionrelates to a new and improved theft alarm operable by-vibration and/orspatial displacement'of the device to which it isattached. A typicalinstallation is on a bicycle which is left unattended. If the bicycle ismoved, the vibration of the movement causes the alarm to sound and thealarm continues to sound until the electric circuit is broken by turninga key switch off.

A feature of the invention is the fact that the movement of the deviceto which the alarm is attached in any plane causes the alarm to sound,whereas other alarms which have relied upon movement .of the vehicle toenergize the alarm'circuit required movement in a specific plane.

the'cover of the casing 11 may be removed to provide Another feature ofthe invention is the fact that only a very small movement is necessaryin order to cause the alarm to sound.

As a still further feature of the invention, the vibratory switch whichcauses the circuit to close may be adjusted in sensitivity so thatonlyvibrations above a certain amplitude cause'the buzzer to sound.

Another feature of the invention is the fact that the unit isself-contained in that it is battery operated and the entire circuit,including circuit components, buzzer and battery are enclosed in a casewhich may be mounted on the device in a manner so that the alarm cannotbe removed. The casing may be'attached to any portion of the devicesuch'as the steering post orhandlebar of a bicycle where the key switchis readily accessible. I

Another feature of the invention is the fact that it is necessary toturn a key in order to inactivate the circuit.The vibratory movementcauses the buzzer to sound continuously until the key is turned.

Other objects of the present invention will become apparent upon readingthe following specification and referring to the accompanying drawingsin which similar characters of reference represent corresponding partsin each of the several views.

. DESCRIPTION OF THE DRAWINGS In the drawings: FIG. 1 is a fragmentary,perspective view of a portion of a bicycle with the alarm attachedthereto.

, FIG. 2 is an enlarged sectional view through the alarm.

FIG. 3 is a sectional view through the vibratory switch.

FIG. 4 is a circuit diagram of the device.

DESCRIPTION OF THE PREFERRED EMBODIMENT Casing 11 of the presentinvention may be affixedto any device to be protected. In theaccompanying FIG. 1, the casing 11 is fixed permanently (by meansforming no part of the present invention) to the steering post 12 of abicycle 13. It will be understood that the alarm may be attached tovarious other devices and in any desired location. The'means ofattachment of the casing 11 to the post 12 is not illustrated in detail,but it will be understood that a permanent attachment means ispreferred.

access to change batteries. Within the casing 11 is a vibratory switch18 which is sensitive to movement in any plane. When the switch 14 ison, vibration closes the switch l8-and energizes the circuit ashereinafter appears. Switch 18 consists of a conductive tube 19 which isclosed at one end by a fiber washer 21. A flexible stem 22 is insertedthrough the central hole in washer 21 with a sliding fit. Stem 22 ispreferably' formed of a material such as piano wire. At the outer end ofwire 22 is a weight 23 such as a split lead shot fixed to the wire 22.To insure against displacement of the shot 23, a bend 24 is formed inthe outer end of wire 22. By' moving the wire relative to washer 21 thesensitivity of the switch 18 may be adjusted because the distancebetween weight 23 and washer 21 affects the amplitude wire 22 flexes forany given vibration. Once adjusted, the wire is fixed in place andfurther adjustment is generally unnecessary.

Oscillation of shot 23 under vibration of switch 18 causes ball 23momentarily to contact tube- 19,

establishing an electrical connection which causes the v circuit for thebuzzer to sound as hereinafter explained.

The electrical components are preferably mounted upon aprinted circuitboard 26 which fits into the easing 11. An electric battery 27 which ispreferably of a small size but of sufficient voltage and power toenergize the buzzer circuit is installedin a compartment in casing 11and is preferably accessible for changing exhausted batteries when thekey switch 14 is open. Mounted on the circuit board is a siliconcontrolled rectifier 29. Switch 18 is connected in series with aresistor 32 to the gate of rectifier 29. The function of the rectifier29 is that when there is a momentary closing of the switch 18, the gatevoltage triggers the rectifier to On state and the circuit is latchedclosed until the switch 14 is opened. The energization of the circuitcauses sounding of a buzzer36 the coil 37 of which is and 33, in apreferred embodiment of the invention, are

wired into the circuit. The values of the resistors 31, 32

continuously until the switch 14 is opened, whereupon the rectifier 29is unlatched.

What is claimed is:

1. An alarm responsive to vibration comprising a casing having means forattachment to a device to be guarded and containing the other componentsof said alarm, said components comprising a key-operated switch having afirst and second switch terminal, a battery having a first batteryterminal connected to said and a straight flexible conductive wire,means mounting said wire axially of said tube, a conductive weight onsaid wire normally centered within said tube when said device isat rest,a non-conductive washer having a central aperture in one end of saidtube, said wire fixed in said aperture, said weight vibrating toestablish electric contact with said tube when said device is moved,said flexible wire connected to said second switch terminal, a secondresistor connected in series with said tube and said electrode gate, athird resistor connected to said gate and said second battery terminal,said third resistor being substantially less than the resistance of saidsecond resistor, said rectifier being energized when said weightcontacts said tube by vibration of said device to conduct the currentthrough said coil from said battery continuing to flow until said keyoperated switch is opened.

1. An alarm responsive to vibration comprising a casing having means forattachment to a device to be guarded and containing the other componentsof said alarm, said components comprising a keyoperated switch having afirst and second switch terminal, a battery having a first batteryterminal connected to said first switch terminal and a second batteryterminal, a latching silicon controlled rectifier having a cathode, ananode and a gate electrode, a buzzer having a coil, said coil connectedbetween said second switch terminal and said anode, a first resistoracross said coil, said caThode connected to said second batteryterminal, a second switch comprising a conductive tube and a straightflexible conductive wire, means mounting said wire axially of said tube,a conductive weight on said wire normally centered within said tube whensaid device is at rest, a nonconductive washer having a central aperturein one end of said tube, said wire fixed in said aperture, said weightvibrating to establish electric contact with said tube when said deviceis moved, said flexible wire connected to said second switch terminal, asecond resistor connected in series with said tube and said electrodegate, a third resistor connected to said gate and said second batteryterminal, said third resistor being substantially less than theresistance of said second resistor, said rectifier being energized whensaid weight contacts said tube by vibration of said device to conductthe current through said coil from said battery continuing to flow untilsaid key operated switch is opened.